Complex Mutual Exclusion Validation Logic

Question

I need to validate some form inputs in complex way. E.g.

<select id="options" multiple="multiple">  
<option>A</option>  
<option>B</option>  
<option>C</option>  
<option>D</option>  
<option>E</option>  
</select>

For example, if user selects A and B, user should be given an error if user also selects D.

Note, I'm trying to keep this business rule in a separate layer from this UI code, which could be an entirely different form, e.g. checkboxes, drag-and-drop, add/delete options with possibly accompanying fields.

I'm looking for a framework, design pattern, or other elegant way to code this logic, preferably ultimately through validation attributes in a model.

score 1 · Answer 1 · answered May 10 '13 at 02:09

1

Approaching the question from a different angle: Why not disable D if the user selects A and B? When I have this kind of question I start to think about reviewing my UI flow.

answered May 10 '13 at 02:09

Vlad GURDIGA

111

score 1 · Answer 2 · answered Jun 24 '13 at 09:45

For representing the validation logic of your inputs, you can use a Karnaugh map, in which inputs are the selection state of A, B, C, D and E, and the outcome is the validation status of each input combination.

  AB-CDE | 000 | 001 | 011 | 010 | 110 | 111 | 101 | 100 |
 --------+-----+-----+-----+-----+-----+-----+-----+-----+
  00     |     |     |     |     |     |     |     |     |
 --------+-----+-----+-----+-----+-----+-----+-----+-----+
  01     |     |     |     |     |     |     |     |     |
 --------+-----+-----+-----+-----+-----+-----+-----+-----+
  11     |     |     |  0  |  0  |  0  |  0  |     |     | -> Error if (A.B).D
 --------+-----+-----+-----+-----+-----+-----+-----+-----+
  10     |     |     |     |     |     |     |     |     |
 --------+-----+-----+-----+-----+-----+-----+-----+-----+

From that map, you can find the minimal logic expression validating your check boxes.

score 0 · Answer 3 · edited May 23 '17 at 12:40

Most frameworks can validate at the model level. So that should be sufficient. So you validate at the lowest possible level.

Example: https://stackoverflow.com/questions/14217442/cakephp-validation-depending-on-other-field

If you want to show this in the interface (with ajax for example) you just call the model to validate (via the controller probably). Create a method in the controller like: validateOptions() and send an ajax call to it so you can modify the user interface.

When really saving the validation will be done again to ensure it's right.

Complex Mutual Exclusion Validation Logic

3 Answers3